Do EV Batteries Drain When Not In Use?

Do EV Batteries Drain When Not In Use?

There are many reasons that you may need to take your car off the road for an extended period.

Perhaps you are going on a long holiday, or maybe you are swapping living at home for going to university.

Whatever the reason, getting a valid SORN (Statutory Off Road Notification) will not be your only concern. You will also want to ensure your car is roadworthy for when you are ready to drive it again, so there is no delay or costly repairs.

New owners of EVs (electric vehicles) may have extra concerns regarding their battery life, especially if they are not driving the car to keep it ticking over.

So, do EV batteries drain when not in use? Is this something we need to worry about?

Will storing my car damage the battery?

If stored correctly, your EV battery will be perfectly fine. As with electronics, batteries deplete over time and EV batteries are no different.

EVs have two batteries, one used to help the car move and the other, a 12-volt battery, which is predominantly used to power electrical components.

As the main EV battery will only drain by as little as a few per cent of the total battery capacity per month, depending on the make and model, this 12-volt battery is the one most likely to be drained when the car is parked for an extended period of time.

To get around this, most people will be tempted to overcompensate and keep their vehicle constantly plugged in and charging.  However, this is more harmful to your battery than you might think.

Should I charge to 100%?

When being used normally, EVs should only be charged to between 20-80%. This is the optimum State of Charge (SOC). This will keep batteries in the best condition, prolong their life, and help ensure they last the full 10-20 years.

Charging to 100% routinely can contribute to an increased likelihood of damage because of the amount of stress an extremely high or low SOC puts on the battery. This also applies to letting the battery drain down to 0%.

This stressful SOC can bring damage to the batteries that is relatively minor, but over time contribute to decreasing battery life.

As such, leaving the car plugged in, and therefore at 100% when not in use does not help you take care of your car and may in fact contribute towards decreasing the life of your car battery.

What percentage should I charge to?

To get around potential battery problems when off-road, most manufacturers have a battery charge sweet spot that they suggest car owners charge to before unplugging and storing the EV. This will differ with each car, and specific information will be given in the vehicle handbook. The Renault ZOE, for example, is recommended to hold a minimum charge of 20%.

This minimum charge percentage allows for the main battery to regularly recharge the 12-volt battery to ensure it can continue to power the car’s various accessories. A well-charged 12-volt battery also ensures that the car can be back on the road again quickly when needed.

Other top tips for preparing your car for off-road periods

  • Park your car in a temperate spot, protected from extreme heat or cold and bad weather. Hot weather is bad for batteries as it can evaporate the battery’s vital liquids and weaken its ability to hold a charge.
  • Put the car into ‘deep sleep’ or ‘power save’ mode, as this will stop excess stored power from being lost.
  • Move the car by a foot or two every once in and while to prevent flat patches from forming on the tyres.

Downtown Electrical are here to help

If you’re still new to the world of electric cars, or simply want to find out more, the team here at Downtown Electrical are here to help.

Not only do we stock high-quality electric car charging stations and battery storage, but we also offer expert advice and tips on how to get the most out of your new device.

For more expert information, contact us today by filling in our contact form or by calling us on 0113 345 6798.

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